Have you solved definitly the problem ? If yes , you had luck .
The reality is the following: nobody knows nothing regarding a solution, that is not the exchange of logic board. Apple Computer doesn't accept that is a serial problem to give us a recall , I've reading many people saying a lot of ******** and nobody gives the true solution, that until now is to exchange logic board . I want a solution that no envolves exchange of logic board .
PS1: I have 8 MacPros early 2008 and have exchanged 3 logic boards and have others with the same problem , and I don't want to give more money for an error of Apple Computer . You know that after long time , Apple accept that graphics adapter of Mac Pro early 2008 had problems and now (after july) is promoting a recall . We have to have this for logic board too . When I talk with them , they say that nobody related this problem before . It's impossible . It's a war and we have to win .
As I have 8 Mac Pros (same model) and I have exchanged 3 logic boards , I've tested every parts of the others and I'm sure that the problem is with logic board (no power supply , no processor , no graphic adapter , no Mac OS version , no memory , no eletrical issue , no UPS problem - Apple doesn't recomend any UPS) . I have lost much time , doing all the possible tests , with system , without system , with 17 , 20 , 24 and 26 degree Celsius , all possibilities and no solutions , except exchange logic board .
PS2 : When one Mac Pro was under garantee , I exchanged a logic board and only two months after , I had to exchange again , because I had the same problem .